Screws, in particular wood screws, in general have the function to attach at least two components, which components consist, e.g., of wood or a wood-like material. Wood screws are predominantly screwed into wood components, wherein they themselves will cut an appropriate counter-thread. A complementary counter-piece such as, e.g., a nut having an internal counter-thread, which usually is required for securing metal screws, does not exist with wood screws. Such wood screws usually have a cylindrical screw shank having a coniform tip at one shaft end or screw end, respectively, thereof, as well as a screw head or drive head, respectively, at opposite shank end thereof. A helical screw thread, which is wound onto a thread core or onto a screw basic body, respectively, may be produced—depending on the intended use—as a complete thread or as a partial thread, and it usually tapers respectively to the screw tip. In the case of the partial thread, there is distinguished between the smooth screw shank without thread and the thread core in the region of the thread section. The smooth screw shank is then usually arranged in-between the thread section and the screw head, wherein a diameter of the screw shank usually is larger than a diameter of the thread core. With screws having complete threads the thread section extends from the screw tip to the screw head, which is why in this case the screw shank is the thread core and, hence, the diameter of the screw shank corresponds to the diameter of the thread core.
Such wood screws—which are often also designated as chipboard screws—are manually or by way of machinery screwed, with the tip thereof advancing, into a more or less soft material, e.g., into components made from wood or a wood-like material. While screwing, the material of the component is then—unlike with drilling—replaced by the wood screw. A wood screw that is screwed into a building as a connecting part has to be able to receive or transfer, respectively, or discharge different force impacts in-between neighbouring components that are screwed together. These force impacts may be tensile, pressure and/or bending forces, depending on the application thereof. With a screwed-in wood screw, a so-called thread retraction force or retraction carrying capacity is essential, this is that holding force, which is provided by the screw thread screwed-in in the component for connecting the components screwed together.
Due to the material replaced, there is generated pressure while screwing in, which then acts on the screw screwed-in as well as within the component material. This pressure may disadvantageously lead to, on the one side, the component being blasted or destroyed, respectively, while screwing in due to the splitting effect of the screwed-in screw. On the other side, there becomes necessary, due to the pressure acting in the component, an increased force effort or an increased screwing torque, respectively, for screwing the screw. If the screwing resistance or the screwing torque, respectively, are too high, then the screw may be screwed off disadvantageously while it is being screwed into the component, which is why in this case the screw cannot receive or transfer, respectively, anymore forces within the component. For the further development of screws, in particular of wood screws, hence, the following parameters are of particular relevance:                Reduction of screwing resistance or screwing torque, respectively:                    A reduction of the screwing resistance or a reduction of the screwing torque, respectively, which are required for screwing in, is desired, as thereby there is enabled easier, less force-consuming screwing by a user, which is why further the risk of injury and accident while screwing in may be reduced. Furthermore, due to a low force and energy effort, there are further reduced the required maintenance and cost efforts of devices for screwing, such as, e.g., screwdrivers on the basis of rechargeable batteries.                        Increase of thread retraction force or retraction carrying capacity, respectively:                    An increase of the holding force of the screw thread in the component or of the retraction carrying capacity, respectively, of a wood screw is desired, as for the attachment using several wood screws there is required a lesser total amount of connecting means due to an increased holding force of each individual screw. Hence, in overall there may be used fewer connecting means for solving said attachment task, which is why also material resources and costs may be sustainably reduced. In contrast thereto, when using the same amount of connecting means with a respectively increased holding forcer per screw in comparison with conventional screws, this will lead to a higher-grade solution of a certain attachment task and, hence, higher-grade safety with wood construction.                        Reduction of the splitting effect on the component while screwing in:                    While screwing in a reduction of the splitting effect on the material of the component is desired as there are only guaranteed high holding forces of the screwing in an essentially crack-free component and as there is achieved a possibly low wear of wood components only in the case of a comprehensively crack-free mounting.                        
From prior art there are known different embodiments of wood screws, aiming at influencing in a rather positive way at least one of the three above-mentioned parameters—reduced screwing resistance as well as reduced splitting effect with increased thread retraction force.
In order to minimize pressure when screwing within the component and, hence, maintain the screwing resistance as low as possible, conventional wood screws are provided, e.g., with a synthetic sliding cover. This, however, will disadvantageously increase production costs and have negative effects on the environment. From prior art there are further known wood screws, in which there is situated a friction part or a so-called countersink, respectively, at the end of the thread in the transition region to the smooth shank part of a screw. The effect and the function of such a friction part are to produce a larger hole diameter in the material of the component than that corresponding to the diameter of the screw shank in the wood, so that, when screwing in, the friction on the following smooth screw shank will be reduced.
Furthermore, there are existent among commercially available wood screws different geometrical embodiments of the screw tips, which each have an at least comparable function as the above mentioned friction part, wherein, however, the friction part is arranged already on the screw tip and not farther back in the transition region from the thread part to the smooth screw shank part, as viewed in the screwing direction. According to embodiment or dependent on the respective producers, respectively, such friction parts in the region of the screw tip are also designated as so-called countersinks, thread rings, counter-threads, driving threads or also as shank rips, drill tips or as scraper grooves. These friction parts arranged at the screw tip all have in common that already when screwing in there is achieved, starting at the tip of the screw, an increased hole diameter in the component, which is why the core diameter of the screw shank, downstream in the screwing direction, on which the thread of the screw is mounted, is exposed to a reduced friction effect. Such embodiments, however, are disadvantageous insofar as due to the increased hole diameter in the component material the thread retraction force or the retraction carrying force, respectively, and, hence, the holding force of the screw thread in the component are reduced.
In regard to the retraction carrying capacity, the holding force of the thread in the component is predominantly determined by way of the thread pitch with commercially available products. In this way, there are commercially available wood screws, which have a so-called high-low-thread (also designated as hi-lo-thread), which aims at increasing the holding force. Such a wood screw is known, for example, from the document AT 412665 B. This wood screw has a so-called compacting tip, wherein transversal rips are inserted in-between the thread flights in the region of the tip. These transversal rips are intended to compact the material by way of replacement, when the screw in turned in, and thus to reduce the friction, when the screw is screwed in. In this way, the retraction force of the screwed-in screw is disadvantageously reduced.
By way of appropriate measures in the region of the screw tip, there is attempted to achieve a reduced splitting effect of wood screws while being screwed into a component, in this way possibly not damaging or destroying, respectively, the material of the component while being screwed in. For this reason, there are known from prior art so-called countersinks, thread rings, counter-threads, driving threads or also shank rips or drill tips, respectively, wherein there is taken into account by the manufacturer that each thread flight is rolled exactly up to the tip. There are further known wood screws, wherein a so-called serrated crown is applied to the screw thread in the region of the screw tip, thereby reducing the undesired splitting effect when screwing into the component material. These measures mentioned are disadvantageous at least in so far as they are rather complex in the production thereof. As the suggestions for improvement that were mentioned above, this is, to produce the screw thread in the region of the screw tip especially exactly or to provide it with an additional serrated crown, respectively, do not constitute any alterations to the fundamental setup of wood screws known per se, also the effects of these suggested measures are rather limited, which is why there may nevertheless occur damage to the component when such wood screws are used.